Chemical modification of diamond surfaces generates a
negative
electron affinity (NEA), which shows great potential in realizing
electron emission. In this study, zirconium (Zr) termination on clean
and oxidized diamond (100) surfaces is theoretically proposed by using
the structure prediction method, and electronic properties of these
predicted surfaces are investigated by first-principles calculations.
On the oxidized surfaces, the adsorption energy at 0.25 monolayer
(ML) Zr coverage reaches a high value of −10.42 eV, further
confirmed by the largest integrated crystal orbital Hamiltonian population
value of 6.61 eV. For clean and oxidized diamond (100) surfaces, the
largest NEA values at 0.25 ML Zr coverage are −3.75 eV and
−3.45 eV, respectively. The dynamic stability of these surface
structures is demonstrated by calculating phonon dispersion curves.
Furthermore, ab initio molecular dynamics simulations
confirm the high thermal stability of the oxidized diamond surface.
Therefore, these results indicate that Zr-terminated diamond (100)
surfaces possess good thermal stability and higher NEA, making them
promising candidate materials for electron emission applications